Question: What is the least common multiple of 21 and 12? Another way to say this is: $\lcm(21, 12) = {?}$
Solution: The least common multiple is the smallest number that is a multiple of 21 and 12. We know that 21 x 12 (or 252) is a common multiple, but is it the least common multiple? Write out the multiples of 21 until we find a number divisible by 12. 21, 42, 63, 84, So, 84 is the least common multiple of 21 and 12.